Without limiting the scope of the present invention, its background will be described in relation to stimulation operations in a wellbore that traverses a subterranean hydrocarbon bearing formation, as an example.
During drilling and construction of wellbores that transverse hydrocarbon bearing formations, it is oftentimes desirable to form a filter cake on the face of the formation to minimize damage to the permeability thereof. The filter cake often comprises an acid-soluble component such as a calcium carbonate bridging agent and a polymeric component such as starch and xanthan. Before desirable fluids, such as hydrocarbons, may be produced from the formation, the filter cake must be removed. One method of removing the filter cake is to inject a treatment fluid, such as a hydrochloric acid solution, into the wellbore.
In addition to filter cake removal, hydrochloric acid solutions are also used in treatments carried out to stimulate the subterranean hydrocarbon bearing formation traversed by the wellbore. For example, the hydrochloric acid solution is injected into the subterranean formation to react with acid soluble materials in the formation and enlarge pore spaces in the formation. These acidizing treatments are designed to improve the formation permeability, which enhances production of reservoir fluids. Typically, such acidizing operations are performed at a high flowrate, but at a treatment pressure below the fracture pressure of the formation such that the acid penetrates an extended distance into the formation while avoiding causing damage to the formation. Attempts have been made to inject treatment fluids as reverse flow through conventional inflow control devices that utilize one or more flow restrictors such as flow tubes, nozzles, labyrinths or the like. It has been found, however, that the flowrate required for acidizing operations is typically higher than the production flowrate from the formation. As such, reverse flow through conventional inflow control devices results in an unacceptably high pressure drop in the treatment fluid.
Accordingly, a need has arisen for an apparatus that is operable to inject a treatment fluid into the wellbore and the surrounding formation. A need has also arisen for such an apparatus that is operable to inject the treatment fluid at a high flowrate. Further, need has arisen for such an apparatus that is operable to inject the treatment fluid without an unacceptably high pressure drop.